In recent years, stereoscopic displaying technologies have been developed quickly and become a focus of research. The stereoscopic display technologies play an important role in fields of medical care, advertisement, military affairs, exhibition, games and the like. FIG. 1 shows a schematic view of a prior art stereoscopic display device. As shown in FIG. 1, the stereoscopic display device mainly includes a liquid crystal display (LCD) 10 and a pair of shutter glasses 13. The LCD 10 mainly includes an LCD panel 11 and a backlight module 12. The LCD panel 11 can display left-eye images and right-eye images alternately as being illuminated by the backlight module 12.
The pair of shutter glasses 13 includes a left-eye glass 131 and a right-eye glass 132. Each of the left-eye glass 131 and the right-eye glass 132 includes two polarizers (not shown) and a liquid crystal layer (not shown) interposed between the two polarizers. By applying voltages to respective liquid crystal layers, the left-eye glass 131 and the right-eye glass 132 can be controlled to be turned on and off, respectively. During the stereoscopic displaying, when the LCD panel 11 displays a left-eye image, the left-eye glass 131 is turned on and the right-eye glass 132 is turned off. In this case, the left-eye image is transmitted to the user's left eye while the right eye views a black image. Conversely, when the LCD panel 11 displays a right-eye image, the left-eye glass 131 is turned off and the right-eye glass 132 is turned on. In this case, the right-eye image is transmitted to the user's right eye while the left eye views a black image. Then, the left-eye image and the right-eye image received respectively by the left eye and the right eye of the user are combined to form a stereoscopic image in the user's brain, thus resulting in a stereoscopic displaying effect. However, because the LCD panel 11 has a response time to the images, a previous image might be seen during switching between the left-eye glass 131 and the right-eye glass 132; and consequently, an erroneous image might be received by the user to cause crosstalk, which has an adverse effect on the stereoscopic displaying effect.
FIG. 2 shows an operational timing diagram of the stereoscopic displaying device shown in FIG. 1. As shown in FIG. 2, to solve the problem of crosstalk between the left-eye image and the right-eye image, a black image is further interposed between the left-eye image and the right-eye image in the prior art stereoscopic display device described above. The left-eye image L, the black image B, the right-eye image R, the black image B and so on are transmitted to the LCD panel 11 of the LCD 10 successively through a scanning way and are displayed by the LCD panel 11 successively from top to bottom.
Additionally, in the prior art stereoscopic display device described above, the backlight module 12 is further divided into an upper backlight region 121 and a lower backlight region 122 as shown in FIG. 1. The upper backlight region 121 and the lower backlight region 122 are turned on alternately according to the content displayed by the LCD panel 11. Specifically, in order to overcome the delay caused by liquid crystal molecules of the LCD panel 11, the upper backlight region 121 is turned on when image data of an upper half image of the left-eye image L or the right-eye image R has been transmitted to the LCD panel 11 (i.e., when the image data of the left-eye image L or the right-eye image R has been transmitted for a duration of a half frame), and is turned off when the image data of the whole left-eye image L or the whole right-eye image R has been totally transmitted to the LCD panel 11 (i.e., when the image data of the left-eye image L or the right-eye image R has been transmitted for a duration of a whole frame). On the other hand, the lower backlight region 122 is turned on when the image data of the whole left-eye image L or the whole right-image R has been totally transmitted to the LCD panel 11, and keeps being turned on for a time interval equal to the turning-on time interval of the upper backlight region 121 before being turned off.
The left-eye glass 131 is turned on when the LCD panel 11 displays the left-eye image L and the upper backlight region 121 is turned on, and is turned off after a duration of two frames. The right-eye glass 132 is turned on when the LCD panel 11 displays the right-eye image R and the upper backlight region 121 is turned on, and is turned off after a duration of also two frames. As a result, the left-eye image L displayed by the LCD panel 11 is transmitted to the user's left eye through the left-eye glass 131, and the right-eye image R displayed by the LCD panel 11 is transmitted to the user's right eye through the right-eye glass 132.
In this way, by turning on the upper backlight region 121 and the lower backlight region 122 alternately and keeping the lower backlight region 122 turned off during the switching between the right-eye glass 132 and the left-eye glass 131, the problem that, due to the delay caused by liquid crystal molecules of the LCD panel 11, a previous right-eye image R or left-eye image L is transmitted to the user's left eye or right eye through the left-eye glass 131 or the right-eye glass 132 to cause crosstalk is solved.
However, when the image data of the upper half image of the left-eye image L or the right-eye image R has been transmitted to the LCD panel 11 in the prior art stereoscopic display device described above, the upper backlight region 121 is turned on, so the light emitted by the upper backlight region 121 may be transmitted to a lower middle region of the LCD panel 11; and when the image data of the whole left-eye image L or the whole right-eye image R has been transmitted to the LCD panel 11, the lower backlight region 122 is turned on, so the light emitted by the lower backlight region 122 may be transmitted to an upper middle region of the LCD panel 11. This makes brightness of the middle region of the LCD panel 11 perceived by the user's eyes greater than that of the upper region and the lower region of the LCD panel 11, thus leading to non-uniformity in brightness of the image displayed by the stereoscopic display device.
Accordingly, a need exists in the art to provide a stereoscopic display device and a control method thereof that can solve the aforesaid problems.